1,096 research outputs found
Multipath routing and QoS provisioning in mobile ad hoc networks
PhDA Mobile Ad Hoc Networks (MANET) is a collection of mobile nodes that can
communicate with each other using multihop wireless links without utilizing any
fixed based-station infrastructure and centralized management. Each mobile node
in the network acts as both a host generating flows or being destination of flows
and a router forwarding flows directed to other nodes.
Future applications of MANETs are expected to be based on all-IP
architecture and be capable of carrying multitude real-time multimedia
applications such as voice and video as well as data. It is very necessary for
MANETs to have an efficient routing and quality of service (QoS) mechanism to
support diverse applications.
This thesis proposes an on-demand Node-Disjoint Multipath Routing protocol
(NDMR) with low broadcast redundancy. Multipath routing allows the
establishment of multiple paths between a single source and single destination
node. It is also beneficial to avoid traffic congestion and frequent link breaks in
communication because of the mobility of nodes. The important components of
the protocol, such as path accumulation, decreasing routing overhead and
selecting node-disjoint paths, are explained. Because the new protocol
significantly reduces the total number of Route Request packets, this results in an
increased delivery ratio, smaller end-to-end delays for data packets, lower control
overhead and fewer collisions of packets.
Although NDMR provides node-disjoint multipath routing with low route
overhead in MANETs, it is only a best-effort routing approach, which is not
enough to support QoS. DiffServ is a standard approach for a more scalable way
to achieve QoS in any IP network and could potentially be used to provide QoS
in MANETs because it minimises the need for signalling. However, one of the
biggest drawbacks of DiffServ is that the QoS provisioning is separate from the
routing process. This thesis presents a Multipath QoS Routing protocol for
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supporting DiffServ (MQRD), which combines the advantages of NDMR and
DiffServ. The protocol can classify network traffic into different priority levels
and apply priority scheduling and queuing management mechanisms to obtain
QoS guarantees
Formation of hot subdwarf B stars with neutron star components
Binary population synthesis predicts the existence of subdwarf B stars (sdBs)
with neutron star (NS) or black hole (BH) companions. We systematically
investigate the formation of sdB+NS binaries from binary evolution and aim to
obtain some clues for a search for such systems. We started from a series of
MS+NS systems and determined the parameter spaces for producing sdB+NS binaries
from the stable Roche-lobe overflow (RLOF) channel and from the common envelope
(CE) ejection channel. Various NS accretion efficiencies and NS masses were
examined to investigate the effects they have. We show the characteristics of
the produced sdB+NS systems, such as the mass of components, orbital period,
the semi-amplitude of the radial velocity (K), and the spin of the NS
component. In the stable RLOF channel, the orbital period of sdB+NS binaries
produced in this way ranges from several days to more than 1000 days and moves
toward the short-period (~ hr) side with increasing initial MS mass. the sdB+NS
systems that result from CE ejection have very short orbital periods and then
high values of K (up to 800km s^-1). Such systems are born in very young
populations (younger than 0.3 Gyr) and are potential gravitational wave sources
that might be resolved by the Laser Interferometer Space Antenna (LISA) in the
future. Gravitational wave radiation may again bring them into contact on a
timescale of only ~Myr. As a consequence, they are rare and hard to discover.
The pulsar signal is likely a feature of sdB+NS systems caused by stable RLOF,
and some NS components in sdB binaries may be millisecond pulsars.Comment: 12 pages, 6 figures, 4 tables. Accepted for publication in A&
Pyrazole scaffold synthesis, functionalization, and applications in Alzheimer\u27s disease and Parkinson\u27s disease treatment (2011-2020)
The remarkable prevalence of pyrazole scaffolds in a versatile array of bioactive molecules ranging from apixaban, an anticoagulant used to treat and prevent blood clots and stroke, to bixafen, a pyrazole-carboxamide fungicide used to control diseases of rapeseed and cereal plants, has encouraged both medicinal and organic chemists to explore new methods in developing pyrazole-containing compounds for different applications. Although numerous synthetic strategies have been developed in the last 10 years, there has not been a comprehensive overview of synthesis and the implication of recent advances for treating neurodegenerative disease. This review first presents the advances in pyrazole scaffold synthesis and their functionalization that have been published during the last decade (2011-2020). We then narrow the focus to the application of these strategies in the development of therapeutics for neurodegenerative diseases, particularly for Alzheimer\u27s disease (AD) and Parkinson\u27s disease (PD)
Automaticity in processing spatial-numerical associations: Evidence from a perceptual orientation judgment task of Arabic digits in frames.
Human adults are faster to respond to small/large numerals with their left/right hand when they judge the parity of numerals, which is known as the SNARC (spatial-numerical association of response codes) effect. It has been proposed that the size of the SNARC effect depends on response latencies. The current study introduced a perceptual orientation task, where participants were asked to judge the orientation of a digit or a frame surrounding the digit. The present study first confirmed the SNARC effect with native Chinese speakers (Experiment 1) using a parity task, and then examined whether the emergence and size of the SNARC effect depended on the response latencies (Experiments 2, 3, and 4) using a perceptual orientation judgment task. Our results suggested that (a) the automatic processing of response-related numerical-spatial information occurred with Chinese-speaking participants in the parity task; (b) the SNARC effect was also found when the task did not require semantic access; and (c) the size of the effect depended on the processing speed of the task-relevant dimension. Finally, we proposed an underlying mechanism to explain the SNARC effect in the perceptual orientation judgment task
ラット ガクカセン アクアポリン5 オヨビ 1 ハツゲン ニ タイスル ジリツ シンケイ セツジョ オヨビ エンサン セビメリン トウヨ ノ エイキョウ
[Purpose] The present study aimed to explore the role of autonomic nerves on the regulation of the expression of water channels, aquaporin 5 and aquaporin 1 (AQP5 and AQP1, respectively) in the submandibular gland (SMG) of rats. [Methods] Cervical sympathetic trunk denervation (CSTD) or chorda tympani denervation (CTD) was performed on 7-week-old male SD rats. From the 15th day after operation, cevimeline hydrochloride (10mg/kg) or pilocarpine (0.3mg/kg) or chloroquine (50mg/kg) was administered orally into CTD rats everyday for 7 days. Protein and mRNA levels of AQP5 and AQP1 in the SMG were determined by Western blotting, Northern blotting, and RT PCR. Activities of cathepsins and proteasomes, the enzyme involved in the protein degradation system, were measured using isolated acinar cells as well as the whole SMG tissue. [Results] Expression levels of AQP5 and AQP1 were not affected significantly at 4 weeks although the gland weight decreased to 80% of the control by CSTD ; However, by CTD both the SMG weight and AQP5 protein level had decreased, while the AQP1 protein level had not. On the other hand, the AQP5 mRNA level was not affected by CTD. Cevimeline hydrochloride, an M3 receptor agonist, recovered the AQP5 protein level which had been reduced by CTD, and increased the AQP1 protein level to more than the control level. Oral administration of pilocarpine showed no effect on the protein levels of AQP5 and AQP1. The AQP5 mRNA level of SMG in the CTD rat was not affected by the administration of cevimeline hydrochloride. The activity of cathepsin D/E was increased by CTD and this increase was inhibited by cevimeline hydrochloride. Submandibular acinar cells were isolated by Percoll gradient centrifugation from rats that received CTD and/or CTD plus cevimeline hydrochloride. Changes of cathepsin D/E activities by CTD and cevimeline hydrochloride were also observed in the isolated cells. Further, the administration of chloroquine, a denaturant of lysosome, recovered the AQP5 protein level decreased by CTD, suggesting the involvement of lysosomal enzyme(s) in the reduction of AQP5 protein level by CTD. [Conclusion] The autonomic regulation of the AQP5 protein level in rat SMG is suggested to be controlled by the lysosomal system, not by transcriptional regulation
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